1. Technical Field
The present invention relates to a light source device and a projector.
2. Related Art
In recent years, as a light source device used in a projector, an electrodeless discharge lamp using a microwave discharge method is under active development. The electrodeless discharge lamp does not have a discharge electrode in a light-emitting tube unlike known electrode discharge type lamps, such as an incandescent electric lamp and a high-pressure mercury lamp. Accordingly, since consumption of a filament or electrode is suppressed, the electrodeless discharge lamp is expected as a long-life light source.
As the electrodeless discharge lamp, there is a structure of emitting light by making a microwave resonate using the antenna principle and supplying the microwave energy to a light-emitting portion of a lamp. For example, JP-A-2007-115534 and JP-A-2007-115547 disclose that a high impedance portion is formed in a light-emitting portion located in the middle of a light-emitting tube, which has a light-emitting material therein, by making a pair of electrodes protrude into the light-emitting tube and disposing the electrodes opposite each other with a predetermined gap therebetween. In addition, a strong electric field is generated by connecting a power source for microwave generation to one of the pair of electrodes and supplying a microwave to the high impedance portion in the light-emitting tube, such that light is emitted from the light-emitting portion.
However, the technique disclosed in JP-A-2007-115534 and JP-A-2007-115547 adopts a structure of emitting light using the antenna principle. Accordingly, light is emitted from the light-emitting portion and at the same time, a microwave which is supplied leaks to the outside. As a result, the microwave may have an adverse effect on other electronic apparatuses and a human body. Moreover, in a known light source device, the total length of a lamp is a length corresponding to the wavelength of a microwave. For this reason, it may be difficult to make the entire device small. In addition, since impedance matching at the input end is not sufficient in the known light source device, it may be difficult to improve the luminous efficiency.